Bacteria the likely cause of fish deaths
Recent fish deaths in Hampton Harbour are being investigated by the Department of Fisheries, with naturally occurring bacteria topping the list of suspects.
While the DoF couldn’t confirm the cause of five fish deaths reported last week, biodiversity section leader Shaun Meredith said trichodesmium was common at this time of year. “Blooms of the cyaonobacterium trichodesmium occur naturally and can deplete water of oxygen, resulting in the death of fish when water temperatures increase and winds and swells are light or there is limited ‘flushing’ of a water body,” he said.
“It is conceivable if periods of low wind, swell and warm water combine that fish deaths from associated anoxic conditions could … occur. At this time of year in Dampier, the surface slicks of tricho can collect in sheltered bays, so … those bays are where you could expect oxygen levels to drop.”
Mr Meredith said trichodesmium was responsible for the deaths in 1996 of farmed pearl oysters near Dampier.
The bacteria’s pink-purple and light green surface slicks can often be mistaken for coral spawn.